1. Field of the Invention
The present invention relates to an active support mechanism for supporting a thin reflecting panel included in, for example, a radio telescope and, more particularly, to a reflecting panel adjusting mechanism capable of adjusting the inclination and height of a thin, lightweight reflecting panel without adversely affecting the accuracy of the reflecting panel and of absorbing the thermal distortion of the reflecting panel without forcibly restraining the reflecting panel from moving.
2. Description of the Background Art
FIG. 8A is a schematic plan view of a conventional reflecting panel adjusting mechanism. FIG. 8B is a sectional view taken on a line passing parts 35a and 36 in FIG. 8A. FIG. 8C is a schematic sectional view taken on a vertical line passing a part 34. The reflecting panel adjusting mechanism supports a reflecting panel at four points on two thin, leaf springs, one rod spring and a fixed member.
Shown in FIGS. 8A, 8B and 8C are a reflecting panel 1, a fixed point 34 for restraining the reflecting panel 1 from movement in a horizontal plane and from rotation, holding points 35a and 35b of leaf springs for absorbing the thermal distortion of the reflecting panel 1 in the directions of the arrows 46 and 47, respectively. The leaf spring provided at the holding point 35b has a low rigidity with respect to the directions of the arrows 39 and a high rigidity with respect to the directions of the arrows 40.
Reference numeral 36 denotes a rod spring as a supporting portion that absorbs the thermal distortion of the reflecting panel 1 in all directions including the direction of the arrow 48. The rod spring 36 has a low rigidity with respect to directions indicated by the arrows 41 and 42. Reference numeral 9 denotes jacks for adjusting the inclination and height of the reflecting panel 1.
Reference numeral 44 denotes a leaf spring. The leaf spring 44 is easy to bend in the directions of the arrow 37, and the same is difficult to bend in the directions of the arrow 38. Reference numeral 45 denotes a large-diameter rigid rod for fixation.
When adjusting the height of the reflecting panel 1, the jacks 9 are operated simultaneously to move the reflecting panel 1 vertically. When adjusting the inclination of the reflecting panel 1, jacks 9 are extended or contracted according to necessity. A spherical washer 49 is interposed between the jack 9 and the leaf spring 44 to enable the leaf spring 44 to tilt. In this time, the springs are distorted to absorb a change in the inclination of the reflecting panel 1 and changes in distances between the support points.
The reflecting panel 1 makes thermal expansion in the directions of the arrows 46, 47 and 48 from the fixed point 34 to relieve thermal stress induced therein by thermal distortion. Since the reflecting panel 1 is supported by the springs having a low rigidity with respect to those directions, the reflecting panel 1 is able to make uniform thermal expansion without being significantly distorted. Therefore, the accuracy of the reflecting mirror surface is not significantly deteriorated.
When adjusting the inclination of the reflecting panel by the reflecting panel adjusting mechanism thus constructed, the reflecting panel is distorted by the reactive forces of the distorted leaf springs and the rod spring if the reflecting panel is very thin and lightweight and is required to have a high accuracy, whereby the accuracy of the reflecting mirror surface is deteriorated.
Similarly to the case of relieving thermal stress, if the reflecting panel is thin and lightweight and has a low rigidity susceptible to the rigidities at the support points, the thermal distortion of the reflecting panel cannot be properly absorbed and the accuracy of the reflecting mirror surface is deteriorated.